The ability to see is recognized to reside mainly in the image processing phase, rather than in the image acquisition phase.
Acquisition is carried out by sensors, which are able to react to physical parameters, and the acquired image data is deprived of any interpretation of the content or significance of what the image data represent.
Image processing is carried out on critical image data and is a first step of the process that enables vision. This first step is far from an interpretation of the content or meaning of what the image data represent, i.e., it is far from any pure intellectual process, and is a mere technical process that is not influenced by data content or meaning
Currently, many different methods of performing image fusion are known.
All these methods have the object of improving information content or intelligibility by combining together image data of at least two or, more generally, of a certain number of images of the same object. In most cases the at least two or more images are acquired using different image acquisition processes in order to integrate the image data information of one kind of image acquisition process with the image data information of another kind of image acquisition process. So, for example, two or more images of the same object or scene may be acquired, each or at least some of the images having different spectral ranges such as visual, infrared or UV spectral range. Other examples may use x-ray images, ultrasound images and/or MRI images as source images of an object. In this case, image data is acquired using different physical effects, each of which is sensible to different conditions or qualities of the imaged object and allows highlighting different particulars of the imaged object.
The importance of image preprocessing for the follow-on step of recognizing certain features and qualities of the imaged object, and thus interpreting the information data of the imaged object or scene, is being recognized as being a major contributor in continuously improving the methods of image processing.